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Geofluid processes in subduction zones and mantle dynamics

Geofluids liberated from the subducting plates migrate upward and play vital roles in various subduction zone phenomena, such as magma genesis, earthquake mechanisms, crustal deformation, ore deposition etc. Geofluids and the processes they are involved in subduction zones also greatly affect the mantle dynamics, including global material circulation and chemical differentiation, and the entrance of CHO fluids into the Earth's interior.

We analyzed the 3-D resistivity structure beneath Naruko volcano, northeastern Japan, with the aim of imaging 3-D distribution of fluids in the crust for its volcanic and seismogenic implications. The data wer...

We studied the origin of deep groundwater in the Joban and Hamadori areas in southern Tohoku, Japan, based on δD, δ18O, 129I/I, 36Cl/Cl, and 3H concentrations. Deep groundwater was collected from the basement roc...

The variation in water content of arc basaltic magmas in the Northeast Japan arc and the Izu arc was estimated using a simple plagioclase phenocryst hygrometer. In order to construct a plagioclase phenocryst h...

Non-volcanic hot springs are generally believed to originate through circulation of meteoric or buried sea water heated at depth. In this study, we report the geochemical characteristics of the Arima and Takar...

Geofluids is important for understanding volcanic and earthquake generation processes. In this study, we obtained a detailed seismic velocity structure in and around the Naruko volcano, northeastern Japan, usi...

A better understanding of fluid-related processes such as poroelastic rebound of the upper crust and weakening of the lower crust beneath the volcanic arc helps better understand and correctly interpret the he...

To understand the mechanism of an intensive non-volcanic seismic swarm in the Kii Peninsula, Japan, we used a dense seismic linear array to measure fine-scale variations of seismic velocities and converted tel...

Investigation of olivine-hosted melt inclusions provides information about the abundance of volatile elements that are often lost during subaerial eruptions of lavas. We have measured the abundances of H2O, CO2, ...

A recent microphysical model for the steady-state frictional behaviour of wet illite/quartz gouges in subduction megathrust settings predicts that velocity-weakening in the seismogenic zone results from a comp...

The 2011 off the Pacific coast of Tohoku (Tohoku-oki) earthquake caused increased seismicity in many inland areas in Japan. A seismic cluster north of the Moriyoshi-zan volcano in Akita prefecture, Tohoku Dist...

A strength profile across the NE Japan interplate megathrust was constructed in the source region of the 2011 Tohoku-oki earthquake (Mw9.0) using friction, fracturing, and ductile flow data of the oceanic crustal...

At the western side of the Hidaka Mountain range in Hokkaido, we identify a clear later phase in seismograms for earthquakes occurring at the uppermost part of the Pacific slab beneath the eastern Hokkaido. Th...

Recent research indicates that the shallow mantle of the Cascadia subduction margin under near-coastal Pacific Northwest, USA is cold and partially serpentinized, storing large quantities of water in this wedg...

Geochemical signatures of arc basalts can be explained by addition of aqueous fluids, melts, and/or supercritical fluids from the subducting slab to the sub-arc mantle. Partitioning of large-ion lithophile ele...

Titanian clinohumite is an accessory phase found in peridotites, and it can be a key repository of volatile and other trace elements in sub-arc mantle. To characterize spectroscopic variations due to volatile ...

The pore fluid pressure distribution in the focal region of the 2008 Iwate-Miyagi Nairiku earthquake was investigated through an analysis of the diversity of focal mechanisms. We inverted stress orientations a...

To understand the effect of plate coupling on very low-frequency event (VLFE) activity resulting from megathrust earthquakes, we performed long-term multiscale earthquake cycle simulations (including a megathr...

The 2008 Iwate-Miyagi Nairiku earthquake (M 7.2) was a shallow inland earthquake that occurred in the volcanic front of the northeastern Japan arc. To understand why the earthquake occurred beneath an active v...

The slab-mantle interface in subduction zones is a site of tectonic mixing of crustal and mantle rocks. It is the interface for fluid flow of slab-derived components into the mantle wedge. To assess the fluid-...

The Lindås Nappe, Bergen Arc, is located in western Norway and displays two high-grade metamorphic structures. A Precambrian granulite facies foliation is transected by Caledonian fluid-induced eclogite-facies...

The three-dimensional distribution of fluids and melts under the NE Japan arc was imaged using its resistivity structure, modeled with geomagnetic transfer functions. The data were collected at 37 stations loc...

By enhancing mass transfer and energy release, the cycle of volatiles and melt is a major component of subduction. Investigating this fluid cycle is therefore critical to understand the past and current activi...

Compressional wave velocities (V p) in quartz aggregate were measured to quantify the effect of pore fluid (H2O) on V p at high pressure-temperature (P-T). Ultrasonic measurements were conducted on dry and wet qu...

Carbon dioxide and methane are major components in geofluids; however, there is little evidence showing how C-H-O fluids evolve in a subduction zone. We investigated fluid inclusions in quartz veins from the E...

We performed melting experiments of hydrous pyrolite at pressures from 3 to 8 GPa and temperatures from 1,100°C to 1,800°C to identify the origin of chemical variation in cratonic garnet peridotites with high ...

This study presents the first numerical model for trace element transportation associated with dehydration and fluid migration from the subducting slab and aims to incorporate both fluid dynamical processes (e...

Island arc low-K tholeiites are basaltic magmas erupting from frontal arc volcanoes of juvenile arcs associated with the subduction of old and cold plates. We investigated the origins of geochemical variation ...

We applied the Markov random field model, which is a kind of a Bayesian probabilistic method, to the spatial inversion of the porosity and pore shape in rocks from an observed seismic structure. Gaussian Marko...

The electrical conductivity of brine-bearing quartzite with fluid fractions of 0.19 to 0.30 and salinity of 3 to 17 wt.% was measured at 800 to 1,100 K and 1 GPa. The conductivity of the brine-bearing quartzit...